Method and device to extend the life cycle of a wind turbine

Abstract

A nacelle includes in turn a nacelle frame, and a yaw bearing having likewise/in turn at least a geared ring for providing a rotatable connection between the nacelle and the tower around a yaw axis. A method includes the steps of: a) disengaging the rotatable connection between the nacelle and the tower; b) lifting the nacelle from the tower by using lifting means, allowing the rotation of the geared ring; and c) rotating the geared ring around the yaw axis until the geared ring reaches a predetermined position with respect to the component to which the geared ring is connectable, either to the nacelle or the tower.

The invention claimed is: 
     
       1. A method to extend the life cycle of a wind turbine comprising a tower, a nacelle comprising a nacelle frame, and a yaw bearing comprising at least a geared ring for providing a rotatable connection between the nacelle and the tower around a yaw axis and at least one gear motor of a yaw drive for providing the rotatable connection between the nacelle and the tower around the yaw axis, the method comprising:
 a) disengaging the rotatable connection between the nacelle and the tower; 
 b) lifting the nacelle from the tower using lifting means, allowing the rotation of the geared ring with respect to a component to which the geared ring is connectable while maintaining and powering in contact the geared ring and the at least one gear motor throughout the lifting, wherein the component to which the geared ring is connectable is either the nacelle or the tower; and 
 c) rotating the geared ring around the yaw axis while the rotatable connection between the nacelle and the tower is disengaged, until the geared ring reaches a predetermined position with respect to the component to which the geared ring is connectable. 
 
     
     
       2. The method according to  claim 1  wherein the method includes a step of determining at least a sector of the geared ring subjected to higher loads and wherein the predetermined position includes a position in which the sector subjected to higher loads is in a less loaded area. 
     
     
       3. The method according to  claim 1 , wherein the yaw bearing comprises:
 the at least geared ring which in turn comprises a first ring connected to a geared crown, and 
 a second ring, wherein the step of disengaging the rotatable connection between the nacelle and the tower comprises disengaging a connection selected between: 
 a connection between the first ring and the tower while a connection between the second ring of the yaw bearing and the nacelle is maintained, or 
 a connection between the first ring and the nacelle while a connection between the second ring of the yaw bearing and the tower is maintained. 
 
     
     
       4. The method according to  claim 1  wherein the step of lifting the nacelle from the tower is carried out by at least an auxiliary connection element placed between the nacelle and the tower, wherein the at least auxiliary connection element includes a degree of freedom to allow vertical movements of the nacelle with respect to the tower and prevents the nacelle from rotating around the yaw axis. 
     
     
       5. The method according to  claim 3 , wherein the step of lifting the nacelle from the tower comprises leaving a gap between the first ring and the component to which the first ring is connectable. 
     
     
       6. The method according to  claim 1 , wherein the method further comprising the step of lowering the nacelle by using the lifting means and connecting the nacelle to the tower through the yaw bearing. 
     
     
       7. The method according to  claim 1  wherein the step of rotating the geared ring of the yaw bearing is done by means of activating the at least one gear motor of the yaw drive. 
     
     
       8. The method according to  claim 7 , wherein in the step of activating the at least one gear motor of the yaw drive, the at least one gear motor is fixed to the nacelle. 
     
     
       9. The method according to  claim 7 , wherein in the step of activating the at least one gear motor of the yaw drive, the at least one gear motor is fixed to the tower. 
     
     
       10. The method according to  claim 4 , wherein the at least auxiliary connection element comprises a first section to be connected to a flange formed on the top end portion of the tower, and a second section connected to the yaw bearing. 
     
     
       11. The method according to  claim 4 , wherein the at least auxiliary connection element comprises a first section to be connected to a flange formed on the top end portion of the tower, and a second section to be connected to the nacelle. 
     
     
       12. The method according to  claim 4 , wherein the wind turbine comprises a braking system that in turn comprises a brake disc and at least one brake caliper, the brake disc located between a flange formed on the top end portion of the tower and the yaw bearing. 
     
     
       13. The method according to  claim 12 , wherein the braking system comprises at least two brakes caliper. 
     
     
       14. The method according to  claim 12  wherein the step of lifting the nacelle from the tower comprises mounting the at least one auxiliary connection element, wherein the at least auxiliary connection element comprises a first section to be connected to the flange formed on the top end portion of the tower and a second section to be connected to the at least one brake caliper. 
     
     
       15. The method according to  claim 10 , wherein the at least auxiliary connection element is distributed along a perimeter of the tower flange and is located inside of the tower. 
     
     
       16. A device to extend the life cycle of a wind turbine comprising a yaw system, wherein the device is placed between a nacelle and an upper part of a wind turbine tower, wherein the yaw system comprises:
 a yaw bearing comprising:
 a geared ring which in turn comprises a first ring connected to a geared crown, and 
 a second ring, and 
 
 at least a geared motor that is fixed to the nacelle or to the tower and which comprises at least a pinion which meshes with the geared ring, 
 wherein the device comprises at least one auxiliary connection element placed between the tower and the nacelle and said at least one auxiliary connection element is configured to provide a separation between the geared ring and a component to which the geared ring is connected while the geared ring and the at least one geared motor are maintained and powered in contact throughout the separation, 
 wherein the at least a geared motor is configured to rotate the geared ring around a yaw axis with respect to the component to which the geared ring is connectable, wherein the component is the tower or the nacelle. 
 
     
     
       17. The device according to  claim 16  wherein the first ring and the second ring are two movable rings which rotate one around the other and one of them is connected to the nacelle and the other is connected to the tower. 
     
     
       18. A method for relocating the yaw bearing of a wind turbine comprising a tower, a nacelle comprising a nacelle frame, and a yaw bearing comprising at least a geared ring for providing a rotatable connection between the nacelle and the tower around a yaw axis and at least one gear motor of a yaw drive for providing the rotatable connection between the nacelle and the tower around the yaw axis, wherein the yaw bearing comprises:
 the at least geared ring which in turn comprises a first ring connected to a geared crown, and 
 a second ring; 
 wherein one of the rings is connected to a nacelle frame whilst the other ring is connected to the tower; 
 the method comprising: 
 a) disengaging the rotatable connection between the nacelle and the tower while maintaining the operation of the geared ring, 
 b) lifting the nacelle from the tower using lifting means, allowing the rotation of the geared ring with respect to a component to which the geared ring is connectable while maintaining and powering in contact the geared ring and the at least one gear motor throughout the lifting, wherein the component to which the geared ring is connectable is either the nacelle or the tower; and; 
 c) rotating the geared ring which comprises the first ring around the yaw axis, with respect to the component to which the geared ring is connectable until the geared ring reaches a predetermined position with respect to the component to which the geared ring is connectable. 
 
     
     
       19. The method according to  claim 18  wherein the method includes a step of determining at least a sector of the geared ring subjected to higher loads and wherein the predetermined position includes a position in which the sector subjected to higher loads is in a less loaded area.